用jsp实现直接下载文件而不是在浏览器中打开的功能

<%
// example:
// <a href="download.jsp?path=img/&name=test.gif">download image</a>

String root = getServletContext().getRealPath("/");
String path = request.getParameter("path");
String name = request.getParameter("name");

response.setContentType("unknown");
response.addHeader("Content-Disposition", "filename=\"" + name + "\"");

try
{
java.io.OutputStream os = response.getOutputStream();
java.io.FileInputStream fis = new java.io.FileInputStream(root + path + name);

byte[] b = new byte[1024];
int i = 0;

while ( (i = fis.read(b)) > 0 )
{
os.write(b, 0, i);
}

fis.close();
os.flush();
os.close();
}
catch ( Exception e )
{
}
%>